Pvc compositions, films, laminates and related methods

ABSTRACT

Polyvinyl chloride compositions and films formed therefrom are described which exhibit improved printability and resistance to weathering. The compositions generally comprise polyvinyl chloride having a certain molecular weight, at least one bio-based plasticizer, at least one UV absorber, at least one hindered amine light stabilizer, at least one heat stabilizer, and at least one acid scavenger. Also described are various vinyl-based laminates using the films which can be for example adhesive laminates. Also described are methods of producing the noted films and laminates.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims priority upon U.S. Ser. No. 62/585,973 filed Nov. 14, 2017; and Ser. No. 62/684,244 filed Jun. 13, 2018, all of which are hereby incorporated by reference.

FIELD

The present subject matter relates to polyvinyl chloride (PVC) compositions, films formed from such compositions, and laminates utilizing such films. The present subject matter also relates to methods of forming the films and applications of the films and laminates. The resulting films and laminates exhibit a variety of beneficial characteristics.

BACKGROUND

Vinyl films plasticized with plasticizers have been used for many years in adhesive labels, tapes and decorative sheets. Vinyl films, particularly polyvinyl chloride (PVC) films, have had wide acceptance for such applications because, among other things, they are inexpensive and weather resistant and can be colored easily with pigments and dyes. In addition, plasticized polyvinyl chloride (PVC) has had particularly wide acceptance because its properties can be modified over a wide range by the incorporation of plasticizers. These films have been used in various graphic applications with success.

Although vinyl films have been useful in graphic and wall covering applications because of their superior flexibility and conformability, there is a continuing need to develop films which exhibit relatively high tensile strength, good elongation, and durability.

A number of graphics applications, such as wrapping of vehicles including busses, trailers and the like, require the use of a conformable film such that a graphics installer can easily apply such a film to a non-smooth or irregular surface. These applications require the vinyl film to further exhibit a unique combination of properties including sufficient adhesion to the underlying surface, yet be removable, and exhibit particular three dimensional (3D) conformability properties.

In certain markets or applications, it is desirable to provide such films that are environmentally friendly and avoid the use of certain “non-green” or environmentally unfriendly plasticizers. Replacing such plasticizers typically results in significant and unacceptable changes in the properties and physical characteristics of the resulting films, and particularly those configured for graphics applications.

Accordingly, a need exists for vinyl films and laminates utilizing such films which avoid the use non-green plasticizers, yet which exhibit comparable or superior properties as compared to films utilizing non-green plasticizers.

SUMMARY

The difficulties and drawbacks associated with previous approaches are addressed in the present subject matter as follows

In one aspect, the present subject matter provides a composition comprising from about 70% to about 90% of one or more intermediate molecular weight PVC resins having a molecular weight in a range of from about 102,000 to about 134,800. The composition also comprises from about 10% to about 30% of one or more bio-based plasticizers. And, the composition additionally comprises at least one UV absorber, at least one hindered amine light stabilizer, at least one heat stabilizer, and at least one acid scavenger.

In another aspect, the present subject matter provides a film comprising one or more intermediate molecular weight PVC resins having a molecular weight in a range of from about 102,000 to about 134,800, and a bio-based plasticizer. The plasticizer is utilized at a concentration within a range of from about 25 phr to about 35 phr based upon the PVC resin.

In yet another aspect, the present subject matter provides a vinyl film including one or more intermediate molecular weight PVC resins, and at least one bio-based plasticizer. The laminate also comprises a layer of a pressure sensitive adhesive. The molecular weight of the intermediate molecular weight PVC resin is from about 102,000-134,800, and the concentration of the bio-based plasticizer in the vinyl film is within a range of from about 25 phr to about 35 phr based upon the intermediate molecular weight PVC resin.

In still another aspect, the present subject matter provides a method for producing a vinyl film. The method comprises forming a layer of a vinyl composition in liquid form on a substrate. The vinyl composition includes at least one intermediate molecular weight polyvinyl chloride (PVC) resin, at least one bio-based plasticizer, at least one UV absorber, at least one hindered amine light stabilizer, at least one heat stabilizer, at least one acid scavenger. The method also comprises heating the layer of the vinyl composition to a first temperature within a range of from 250° F. to 350° F. for a time period of from 10 seconds to 2 minutes to thereby form an intermediate vinyl layer. The method also comprises heating the intermediate vinyl layer to a second temperature within a range of from 350° F. to 450° F. for a time period of from 15 seconds to 3 minutes to thereby form the vinyl film.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross sectional view of an embodiment of a vinyl film in accordance with the present subject matter.

FIG. 2 is a schematic cross sectional view of an embodiment of a laminate in accordance with the present subject matter.

FIG. 3 is a schematic cross sectional view of another embodiment of a laminate in accordance with the present subject matter.

FIG. 4 is a schematic perspective view illustrating an embodiment for producing vinyl films in accordance with the present subject matter.

FIG. 5 is a photograph illustrating an embodiment of a laminate adhered to a corrugated panel.

FIG. 6 is a photograph illustrating another embodiment of a laminate adhered to a corrugated panel.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present subject matter provides flexible vinyl films with a unique combination of properties. The vinyl films are formed from composition(s) that include one or more PVC resins which include an intermediate molecular weight PVC resin, at least one bio-based plasticizer, at least one UV absorber, at least one hindered amine light stabilizer (HALS), at least one heat stabilizer, and at least one acid scavenger.

The present subject matter also provides laminates utilizing the vinyl films and particularly those described herein. Generally, the laminates include a vinyl layer, and one or more adhesive layer(s) proximate the vinyl layer. In many versions, the adhesive layer is in direct contact with a face or underside of the vinyl film. These laminates, variations thereof, and additional products are described herein.

The present subject matter further provides methods of producing the noted laminates and/or vinyl films. The vinyl films can be produced using a variety of techniques and particularly using a casting process and particularly an organisol casting process. These and other aspects of the present subject matter are described herein.

I. Vinyl Compositions and Vinyl Films

As noted, the vinyl compositions and vinyl films of the present subject matter comprise one or more PVC resins and particularly at least one intermediate molecular weight PVC resin, at least one bio-based plasticizer, at least one UV absorber, at least one hindered amine light stabilizer (HALS), at least one heat stabilizer, and at least one acid scavenger. Each of these components is described in greater detail as follows.

Polyvinyl Chloride Resins

A wide array of PVC resins(s) can be used in the vinyl compositions and vinyl films of the present subject matter. Polyvinyl chloride is a thermoplastic polymer having a chemical formula (C₂H₃Cl)_(n). In many embodiments, the molecular weight of the PVC resin(s) used in the vinyl compositions is in a range of from about 25,000 to about 250,000. However, it will be understood that the present subject matter includes the use of PVC resins having molecular weights outside of this range.

One or more PVC resins may be used. If multiple resins are used, they are typically blended with one another to form a homogenous blended resin composition. In certain embodiments, a particular combination of polyvinyl chloride resins are utilized in the vinyl compositions and/or vinyl layers of the present subject matter. For example, in one embodiment, a blend of a low molecular weight PVC resin, an intermediate molecular weight PVC resin, and a high molecular weight PVC resin is utilized. These terms “low molecular weight,” “intermediate molecular weight,” and “high molecular weight” refer to PVC resins having K-values and/or molecular weights as follows.

TABLE 1 PVC Resins for Use in Vinyl Compositions and Vinyl Layers Typical Particular Typical Particular Molecular Molecular PVC Resin K-Values K-Value Weights Weights Low Molecular 48-72 68  34,700-101,900 87,600 Weight Intermediate 72-80 76 102,000-134,800 117,700 Molecular Weight High Molecular 80-92 83 134,900-195,500 148,700 Weight

K-values, as known in the art, are an indication of average molecular weight of a polymeric sample or resin, K-values are a measure of molecular weight based on viscosity measurements, and are described in greater detail in “Encyclopedia of Polymer Science and Technology,” Vol. 14, John Wiley & Sons (1971); and “Molecular Weight and Solution Viscosity Characterization of PVC,” Skillicorn, D. E., Perkins, G. G. A., Slark, A., and Dawkins, J. V., Journal of Vinyl Technology, June 1993, Vol. 15, No. 2, Page 107.

The K-values noted in Table 1 above, are merely representative in nature and in no way limit the range or type of PVC resins, or combination of resins, that can be utilized in the PVC compositions and vinyl films or layers of the present subject matter.

In certain embodiments, a blend of a low molecular weight PVC resin, an intermediate molecular weight PVC resin, and a high molecular weight PVC resin is used to provide a relatively high initial reflectivity of a laminate as described herein, as compared to a corresponding laminate utilizing a vinyl layer with a single PVC resin. In addition, in many embodiments, vinyl layers utilizing a blend of a low molecular weight PVC resin, an intermediate molecular weight PVC resin, and a high molecular weight PVC resin exhibit desirable low modulus, and an acceptable low extent of shrinkage.

A variety of PVC resins can be used for the low, intermediate, and high molecular weight PVC resins. Many of these resins are commercially available as follows. Nonlimiting examples of the high molecular weight PVC resin include Mexichem Vestolit G171, Formosa Formolon F-NVW, and SCG Chemicals PG770. Nonlimiting examples of the intermediate molecular weight PVC resin include Mexichem Vestolit G178, Formosa Formolon-1071, and SCG Chemicals PG740. Nonlimiting examples of the low molecular weight PVC resin include Mexichem Vestolit G173, Formosa Formolon-24A, and SCG Chemicals PG620. It will be understood that the present subject matter is not limited to any of these PVC resins and may include other PVC resins.

In certain embodiments, the PVC resin(s) exhibit a relatively low plasticizer solubility which impedes migration of one or more components and particularly protective additives in the composition.

In certain embodiments, the PVC resin(s) also exhibit a high solvent solubility.

In certain embodiments, a high-molecular weight PVC is used to impede the migration of one or more components and particularly protective additives in the vinyl composition. This PVC resin can also be less soluble with the plasticizer(s), thus promoting the plasticizer to function on the surface of the PVC molecule. This PVC can also be more compatible with the solvent(s) used in the composition.

In particular embodiments, the vinyl composition comprises a PVC resin that is an intermediate molecular weight PVC resin. The vinyl compositions can utilize this resin as a majority component of PVC resin(s) or in certain versions, as the exclusive PVC resin. As previously noted, the molecular weight of the intermediate molecular weight PVC resin is within a range of from about 102,000 to about 134,800. The proportion of the intermediate molecular weight PVC resin in the vinyl composition is typically at least 50%, in other embodiments at least 70%, and in other embodiments at least 75% Typically, the maximum proportion of the intermediate molecular weight PVC resin in the vinyl composition is about 95%, with 90% being the maximum for most compositions.

Plasticizer(s)

A wide array of plasticizers) can be used in the vinyl compositions and vinyl films of the present subject matter.

In certain embodiments, the plasticizer(s) selected is bio-based. The term “bio-based” as used herein refers to a plasticizer that includes or is formed from biological products or renewable agricultural materials including plant, animal, and/or marine materials. An example of a bio-based plasticizer is a plasticizer prepared from soybeans, corn, and/or other agricultural products for example. Another example of a bio-based plasticizer is a plasticizer made from natural oils and fats. Typically, bio-based plasticizers exhibit better biodegradability as compared to non-bio-based plasticizers due to the presence of epoxides. In particular embodiments the bio-based plasticizer(s) has an inherent heat stabilizing property, but has less solubility with other additives and/or components of the composition. Although a monomeric plasticizer can be used in certain embodiments, due to its low molecular weight, monomeric plasticizers are typically not used for long-term weathering applications. Thus, more complex polymeric plasticizers with higher molecular weights are used in the vinyl compositions in accordance with the present subject matter.

Non-limiting examples of commercially available bio-based plasticizer(s) which can be used in the vinyl compositions include Drapex® Alpha 200, Drapex® Alpha 200C, Drapex® Alpha 210, and Drapex® Alpha 220 available from Galata; Edenol® D 81, Edenol® D 82 S, Edenol® B 316 Spezial, Edenol® 670, Edenol® 680, Edenol® 1234, Edenol® 9789, Edenol® 1208, and Edenol® 1233 Spezial available from Emery Oleochemicals; Polysorb® ID available from Roquette; Oxblue® DOSX and Oxblue® ABTC available from Oxea; DOSX available from Myriant; and Proviplast® 1044, Proviplast® 2644, Proviplast® 01422, Proviplast® PLS Green 5, and Proviplast® PLS Green 8 available from Proviron. It will be understood that the present subject matter is not limited to any of these plasticizers, and may use other plasticizers.

In many embodiments, the plasticizer(s) used in the vinyl compositions exhibit a relatively high degree of incompatibility and/or are insoluble with respect to water. A preferred class of plasticizers are those derived from adipic acid and polyhydric alcohols. A nonlimiting example of such plasticizer is Palamoll® 656 (CAS No. 208945-12-4), commercially available from BASF.

In particular applications, it has been found that using a higher molecular weight plasticizer leads to an improved and lower permeation rates of water vapor transmission rate (WVTR) and oxygen transmission rates (OTR) of a resulting vinyl film. High WVTRs of vinyl films are believed to contribute to degradation of metal substrates upon which a vinyl film is disposed by the transport of metal ions that can unzip the vinyl molecule. The degradation of the vinyl produces hydrochloric acid (HCl). For retro-reflective vinyl film constructions, both the metal ions and the HCl can interact and consume with the metal layer. Once the metal layer is consumed or distorted, the retro-reflectivity of the construction is compromised. High OTR contributes to oxidative degradation of vinyl films. In the presence of UV radiation, photo-oxidation occurs, producing carbon dioxide (CO₂). Once this occurs, the vinyl film breaks down, forming HCl. Thus, for many embodiments, using a relatively high molecular weight plasticizer reduces WVTR and OTR through the vinyl film, thereby reducing potential for degradation of an underlying metal substrate.

However, it has also been found that relatively high water vapor transmission rates of a vinyl film allow beneficial absorption of printing composition(s) into the vinyl film. Thus, for many of the vinyl films and laminates of the present subject matter, it is desirable that the vinyl films and layers exhibit some degree of moisture permeability particularly to solvent inks of a printing composition.

In certain embodiments, the plasticizers) exhibits heat stabilizing properties.

In certain embodiments, the plasticizer(s) exhibits low solubility with other additives and/or components of the vinyl composition.

The bio-based plasticizer(s) can be utilized in a wide range of concentrations in the vinyl compositions of the present subject matter. The proportion of the bio-based plasticizer(s) in the vinyl composition is typically in a range of from about 10% to about 30%, and in certain versions from about 20% to about 25%. In particular versions, the amount of bio-based plasticizers is within a range of from about 25 to about 35 parts of plasticizer based on 100 parts of the PVC resin.

UV Absorbers

An array of UV absorbers or stabilizer(s) can be used in the vinyl compositions and vinyl films of the present subject matter. The most common types of UV stabilizers are cyanoacrylates, benzophenones, benzotriazoles, triazines and oxanilides. It has been discovered that certain UV stabilizers are migratory—detrimentally affecting physical properties of resulting vinyl films and laminates; others have unexpected plasticizing properties which are lost if the UV stabilizer is not stable in the vinyl film. Accordingly, certain embodiments of the present subject matter utilize one or more particular UV stabilizers that have been discovered to avoid reductions in physical properties, and may lead to improved properties.

In embodiments of reflective constructions, the UV stabilizer(s) are oxanilide or oxanilide-based compounds. A preferred UV stabilizer of this type is available commercially from various sources under the designation Hostavin 3206 and/or Hostavin VSU. Another preferred oxanide UV absorber is Tinuvin 312 available from BASF. In other embodiments, cyanoacrylate and triazine based UV stabilizer compounds are utilized. A preferred cyanoacrylate is Uvinul 3039 from BASF. Preferred triazine types are Tinuvin 1577 and Tinuvin 1600 from BASF. It is also contemplated that Tinuvin 1600 which is a triazine, can be used as a suitable UV stabilizer in the vinyl compositions.

Hindered Amine Light Stabilizers

An oligomeric hindered amine light stabilizer (HALS) is useful for many embodiments and also commercially available under the designation Hostavin N30. Additional examples of hindered amine light stabilizers which are commercially available and which can be used in the vinyl compositions include Hostavin 3068; Tinuvin 123 and 292; and Uvasorb HA10 and HA88FD. The Hostavin agents are available from Clariant. The Tinuvin agents are available from BASF. And the Uvasorb agents are available from 3V. It is also contemplated that Cyasorb UV-3529 from Cytec Solvay Group could be used. The HALS are used as enhancers to a primary UV stabilizer. The UV stabilizer to HALS ratio can range from 9:1 to 6:4. Combinations of any of these UV stabilizers and HALS can be used.

Heat Stabilizer(s)

A variety of heat stabilizers) can be used in the vinyl compositions and vinyl films of the present subject matter. Many of the heat stabilizers include barium (Ba) and zinc (Zn). For these versions, an increased Ba/Zn ratio has been found to reduce one or more detrimental effects that may arise when utilizing other heat stabilizers.

In particular embodiments, it has been discovered that selecting a heat stabilizer that is relatively incompatible in terms of solubility with the plasticizer(s) used in the vinyl compositions leads to improved performance of the resulting vinyl films and/or laminates.

In certain embodiments using heat stabilizers that include both barium and zinc, i.e., “barium-zinc heat stabilizers” as referred to herein, it is preferred to utilize stabilizer(s) having a molar ratio of Ba/Zn which is greater than 3.85:1, and in certain versions greater than 4:1, respectively. In certain applications, suitable heat stabilizer(s) may include phosphorus (P).

Examples of commercially available heat stabilizers that have been found to promote improved performance of the vinyl films and laminates include Mark 4887 and Mark 4825 available from Galata Chemicals, Mark 4887 and Mark 4825 are both barium-zinc heat stabilizers. A variety of other and potentially useful heat stabilizers are available from other suppliers including for example Valtris Specialty Chemicals, Adeka, Baerlocher, Reagens, Kolon Industries, and Halstab. However, it will be appreciated that the present subject matter is not limited to any of these heat stabilizers, and may instead utilize one or more other heat stabilizer(s).

For barium-zinc heat stabilizers, it was found that selecting a heat stabilizer with a higher barium content improves solvent ink dot diameter. And selecting a heat stabilizer with a lower zinc content tends to reduce the solvent ink dot diameter, and have a greater impact than a higher barium content. Thus, for a heat stabilizer containing two metals and particularly for barium-zinc heat stabilizers, the noted ratios of barium to zinc described herein have been discovered to surprisingly produce vinyl films and laminates with excellent characteristics.

Acid Scavengers

A variety of acid scavengers can be used in the vinyl compositions and vinyl films of the present subject matter. It is presumed that the eventual degradation of the vinyl film is inevitable. Once the HCl starts to form, the rate of vinyl degradation is exponential. Acid scavengers are used to counteract the initial formation of HCl and thus prolong the life of the article.

Epoxides are the most common type of acid scavenger used in vinyl films. Epoxides are cyclic ethers with a three atom ring. In many embodiments, use of one or more epoxide(s) in the vinyl compositions has been found to promote various properties and characteristics of vinyl films and laminates using the vinyl compositions. In certain applications, epoxides provide the dual functionality of acting as a plasticizer and an acid scavenger. This improves the flexibility of the vinyl film and enhances the heat stability by delaying the onset of degradation from thermal sources.

However, incorporation of epoxides in the vinyl composition also results in reduction in reflectivity if applicable for retro-reflective constructions and/or other undesirable optical properties of the vinyl films and laminates. The epoxides are migratory and can migrate into and plasticize the film. Once the film or layer is plasticized, it can be more easily deformed by high heat. Once the film or layer is deformed, any metal layer(s) if present, no longer function to create a retro-reflective product.

There are other methods to scavenge acids, however, many are solid particles such as hydrotalcites. For certain laminates, it is desired to avoid anything between a metal layer and an outer surface of the vinyl layer that may defract or diffuse light. Solid acid scavengers defract too much light to be useful. The ideal candidate is a compatible liquid with a low refractive index. BASF has shown that 1-methylimidazole is a useful liquid acid scavenger.

Optional Print Enhancing Additive(s)

The vinyl compositions may also comprise one or more polydimethyl siloxane(s), which are typically known in the art as PDMS. Although a wide array of PDMS agents can potentially be used in the vinyl compositions, in many embodiments it is preferred that the PDMS exhibits a viscosity greater than 40 cSt. Nonlimiting examples of potentially suitable PDMS agents include DMS-S15, DMS-S21, and DMS-S27 available from Gelest; Xiameter OFX-5211 and Xiameter PMX-0156 available from Dow Corning; PSF-50cSt, and PSF-100cSt available from ClearCo; and PDMS agents available from Sigma Aldrich. In certain applications, it has been found that selection and use of certain print enhancing additives as described herein leads to improved circularity of print dots. For example, using a polyacrylate-based surfactant improves dot circularity as compared to a vinyl composition free of such agent. Use of polydimethyl siloxane in a vinyl composition improves uniformity of print dots. Utilizing both of these agents has been discovered to produce print dots having improved dot shape and size as compared to the use of vinyl compositions containing only one of these agents.

Additional Aspects

In certain embodiments, the heat stabilizer, UV stabilizer, and acid scavenger, are all selected so that they exhibit improved compatibility, and in certain versions optimal compatibility with each other, and the solvent. In certain embodiments, the Ba/Zn ratio of the heat stabilizer can be increased to reduce the negative impact on printing. In certain embodiments, a hindered amine light stabilizer (HALS) is utilized and added to the UV stabilizing package. The HALS is typically a solid that is less soluble in the solvent, which will ensure that some UV protection remains in the vinyl. However, for retro-reflective products, a liquid HALS is preferred when available. A higher molecular weight acid scavenger can also be used.

In particular embodiments, a surfactant and PDMS combination is utilized for improved printability. A series of mixture designs found that a surfactant/PDMS weight ratio of 4.8:1, respectively, produced the optimal dot diameter for digital solvent printing. In certain embodiments, the overall concentration of surfactant and PDMS does not exceed 1.60% by weight in the final vinyl film.

The resultant vinyl composition is more weatherable, thus delaying the generation of product-killing acid. The tailored solubility of the additives, combined with the higher molecular weight of the PVC, reduces migration of key additives to the surface that would be deleterious to printing and adhesion to a urethane bonding layer used in many laminate products. The resulting product is clear and glossy, as desired, and the resulting product exhibits improved solvent digital printability.

As previously noted, the vinyl compositions may comprise one or more light stabilizer(s), and particularly one or more hindered amine light stabilizer(s) or HALS as known in the art. These are typically in addition to the UV stabilizers previously noted. In many versions these agents are in solid form at ambient conditions. Moreover, in many embodiments the HALS exhibit low solvent solubility to impede migration of components or additives in the vinyl composition.

In particular embodiments, the vinyl compositions and/or vinyl films comprise particular amounts and/or weight proportions of the noted components. Tables 2 and 3 summarize various embodiments of vinyl compositions (in film form and without solvent) in accordance with the present subject matter.

A significant benefit relating to the vinyl compositions of the present subject matter are the unique physical properties that can be achieved for long term performance on three dimensional applications such as full vehicle wraps. These applications are not possible with other resin types. A specific property that leads to this success is stress relaxation. Most polymers, when stretched, want to rebound (like a rubber band). The vinyl compositions of the present subject matter exhibit intrinsically high relaxation properties and characteristics. So when films formed from the compositions are stretched, such as into corrugation(s) or around complex vehicle geometries, such films will relax and hold that stretch to maintain adhesion into those recesses rather than wanting to rebound or pop-out like other polymers and other grades of PVC. These properties are further described herein regarding a stress relaxation test.

An additional feature of the vinyl compositions utilizing a bio-based plasticizer relates to low color. A concern with bio-derived components is that they typically exhibit a dark or yellow shade. The present subject matter enables the use of such plasticizers even in overlaminate films that require clear transparency.

Another feature of the present compositions is a low migratory property. Other bio-derived plasticizers and components, including the epoxides noted herein, are known to migrate as described herein, which limits use to very low loading levels because they can migrate to the adhesive and affect adhesion. In contrast, the compositions of the present subject matter using bio-based plasticizers do not migrate and allow use of higher levels to achieve significant bio content.

In certain embodiments, the vinyl compositions of the present subject matter exhibit a bio-based content of from about 10% to about 30%, with many versions exhibiting a bio-based content of 17%. The term “bio-based content” as used herein refers to biological products composed of renewable domestic agricultural materials including plant, animal, and aquatic materials, forestry materials, intermediate materials, or feedstocks. A procedure to quantify bio-based content is ASTM D6866. According to the USDA guidelines for defining the amount of bio-based content, the 17% in the noted embodiment composition, represents the amount (by weight) of renewable organic carbon to the total organic carbon (renewable+petroleum based) as measured by the ASTM D6866 test method.

TABLE 2 Representative Embodiments of Vinyl Composition Component Typical Range (wt %) Intermediate MW PVC  70-90 Resin(s) Bio-Based Plasticizer(s)  10-30 UV Absorber(s) 0.1-15 HALS 0.1-10 Heat Stabilizer(s) 0.1-10 Acid Scavenger(s) 0.1-10

TABLE 3 Particular Embodiments of Vinyl Composition Components Typical (phr) Intermediate MW PVC Resin(s) 100 Bio-Based Plasticizer(s)  25-35 UV Absorber(s) 0.1-15 HALS 0.1-10 Heat Stabilizer(s) 0.1-10 Acid Scavenger(s) 0.1-10 Solvent(s) and/or Diluent(s)

The vinyl compositions can include one or more solvent(s). A wide array of solvents can be used, many of which are commercially available such as HiSol 10 and Aromatic 100, both of which are blends of various petroleum distillates. Incorporation of solvent(s) in the vinyl composition promote blending and mixing of components, application of the composition, and/or formation of a vinyl layer or film. The solvent(s) are typically removed from the composition during drying, curing, and/or layer formation.

II. Films and Laminates

The present subject matter also provides a wide array of products utilizing the vinyl films. In many embodiments, the products are adhesive laminate products. These and other aspects are described in greater detail herein.

FIG. 1 is a schematic cross sectional view of an embodiment of a vinyl film 20 in accordance with the present subject matter. The film 20 is formed from the vinyl compositions of the present subject matter. The film defines a first face 22 and an oppositely directed second face 24. Typically, the thickness or gauge of the film is within a range of from 1.20 mils (30.5 microns) to 2.00 mils (50.8 microns), and in many embodiments about 1.50 mils (38.1 microns). However, it will be understood that the present subject matter includes vinyl films having thicknesses outside of this range. If the vinyl film is too thin, the resulting reduction in modulus and tensile strength may render the film susceptible to breaking or tearing when removing or otherwise processing or using. If the tensile strength is too low, the matrix also breaks easily when performing post film processing operations such as “weeding” sign cut letters. The noted maximum thickness of the vinyl film achieves a good balance between conformability and strength of the film. Thicknesses greater than that noted herein may exhibit unacceptable conformability characteristics.

Adhesives

In many embodiments, the laminates of the present subject matter include one or more layers or regions of adhesive. In many embodiments of the laminates, such as laminate 40 depicted in FIG. 2, the layer of adhesive, i.e., layer 30, includes one or more structural adhesives. An example of such a material includes, but is not limited to, urethane adhesives. However, pressure sensitive adhesives with suitable bond strength and refractive index may also be suitable as a layer adhesive. As noted, in many versions the adhesives used in the layer of adhesive, i.e., layer 30 depicted in FIG. 2, include pressure sensitive adhesive(s).

As noted, in many embodiments, the adhesive layer may include one or more urethane adhesives. In many formulations, the urethane adhesive is prepared by combining a polyol component and an isocyanate component with optional crosslinker(s). In many of the urethane adhesives identified for use in the present subject matter, it was discovered that crosslinking and/or chemical bonding with certain functional groups in the adjacent vinyl layer, such as —OH groups, particularly those in the plasticizer(s) in the vinyl layer, leads to improved adhesion and physical affixment between the vinyl layer and the first adhesive layer.

Nearly any pressure sensitive adhesive (PSA) composition known in the art can be used in the present subject matter laminates. Such adhesive compositions are described in, for example, “Adhesion and Bonding,” Encyclopedia of Polymer Science and Engineering, Vol. 1, pp. 476-546, Interscience Publishers, Second Ed., 1985. Such compositions generally contain an adhesive polymer such as natural or reclaimed rubbers, styrene-butadiene rubber, styrene-butadiene or styrene-isoprene block copolymers, polyisobutylene, poly(vinylether) or poly(acrylic)ester as a major constituent. Other materials may be included in the pressure sensitive adhesive composition such as resin tackifiers including rosin esters, oil-soluble phenolics and polyterpenes; antioxidants; plasticizers such as mineral oil or liquid polyisobutylene. Fillers are typically not used in the adhesive layer in highly reflective articles, as this can scatter light and reduce the retro-reflectivity of the article. Fillers can be used in applications that are limited to a maximum reflectivity. The selection of the pressure sensitive adhesive to be used in any laminates of the subject matter is not critical, and those skilled in the art are familiar with many suitable pressure sensitive adhesives for particular applications.

In certain versions, particular types of adhesives and more specifically, pressure sensitive adhesives can be used in conjunction with the films and laminates of the present subject matter. For example, for many applications the films are provided with a layer or region of a permanent adhesive. In other applications, the films are provided with a layer or region of a removable adhesive. The term “permanent adhesive” as used herein refers to adhesives in which the peel force required to peel the film applied to selected substrates amounts to more than 8 Newtons per inch after 24 hours according to PSTC-101 without leaving remnants of the adhesive on the substrate. The term “removable adhesive” as used herein refers to an adhesive in which the peel force required to peel the film applied to selected substrates is less than or equal to 8 Newtons per inch after 24 hours according to PSTC-101 without leaving remnants of the adhesive on the substrate. As is known by those skilled in the art, PSTC-101 is a standard test method to measure peel adhesion strength in pressure sensitive articles and laminates. PSTC-101 is a Harmonized International Standard from the Pressure Sensitive Tape Council.

The adhesive layer(s) may be patterned. These layers can optionally include one or more non-continuous regions of adhesive and/or include regions that are free of adhesive.

It will be appreciated that each of the above described adhesives may be provided as solvent based, emulsions, hotmelt adhesives, UV curable, or radiation curable. Additionally, each of the adhesives may be made removable or permanent. The system and performance characteristic of the adhesives may be selected as desired for a particular purpose or intended use.

Release Liners

In many embodiments, the vinyl-based laminates of the present subject matter include one or more release liners. The liners typically cover or overlie otherwise exposed faces or regions of the adhesive layer, which is typically a PSA.

Release coated liners useful in the laminates of the present subject matter may comprise a release coated laminate comprising more than one sheet material including alternating layers of paper and polymer to provide desirable properties. The following examples of laminates illustrate these types of laminates which may be utilized as the release-coated liners in the laminates of the present subject matter: release composition/polyethylene/paper; release composition/paper/polyethylene; release composition/polyvinylchloride/paper; release composition/polyethylene/paper/polyethylene/tissue; etc. In these examples of release coated liners, the polyethylene films may range from low density to high density, and the paper materials may be any paper materials.

In many embodiments, the laminates include one or more layers and/or regions of print. The print or printing composition can be applied or otherwise deposited on the vinyl film or layer, or other layers of the laminate. It is also contemplated that one or more auxiliary layers such as top coats and over-laminate films can be applied to the vinyl layer and print then disposed on the top coat(s) or overlaminate films. The present subject matter also includes applying top coat(s), protective layer(s), or overlaminate films on the print surface of a laminate. FIG. 3 schematically illustrates a laminate 60 comprising a vinyl film 20 having oppositely directed faces 22 and 24, a top coat or overlaminate 50, and an adhesive layer 30. If print or graphic elements are included, such are typically disposed on the face 22 of the vinyl film. However, the present subject matter includes a wide array of alternate arrangements and configurations.

A wide array of print compositions can be used in association with the present subject matter. Many such compositions are known in the art and/or are commercially available. Nonlimiting examples of such print compositions include inks, coatings, paintings, and toner. The print compositions can be applied by known techniques. In many versions of the present subject matter, print composition(s) are applied directly to an outer face of the vinyl layer of a laminate. As described herein, as a result of characteristics of the vinyl layer, improved properties of the resulting printed layer, region, text, and/or design are attained.

As previously noted, FIG. 3 depicts a preferred arrangement of layers and components in a laminate of the present subject matter. However, it will be understood that the present subject matter includes other arrangements and/or configurations. The present subject matter is not limited to any of these particular versions and includes laminates exhibiting combinations of these features and embodiments.

The laminate structure may have a thickness as desired to provide a laminate having suitable characteristics and properties as desired for a particular purpose or intended use. In one embodiment, the laminate structure has an overall thickness of from about 1.5 mils to about 15 mils (about 35 microns to about 350 microns). In another embodiment, the laminate structure has an overall thickness of from about 3 mils to about 10 mils (about 70 microns to about 254 microns). In still another embodiment, the laminate structure has an overall thickness of from about 5 mils to about 8 mils (about 120 microns to about 205 microns).

The adhesive laminates of the present subject matter exhibit one or more of the following properties: (i) a tensile strength within a range of from about 3,000 pounds-force per square inch to about 3,900 pounds-force per square inch; (ii) an elongation of from about 105% to about 175%; (iii) after exposure to 650 mega joules of UV radiation at an irradiance of 1,500 W/m² at a temperature of 70° C., the laminate exhibits a delta E color change of from 4.0 to 4.8, without any physical defects including delamination from the substrate and cracking of the laminate. In certain embodiments, the adhesive laminates exhibit two or more of these properties. And in particular embodiments, the adhesive laminates exhibit all three of these properties.

III. Methods

FIG. 4 is a schematic perspective view illustrating an embodiment for producing vinyl films in accordance with the present subject matter. FIG. 4 depicts production equipment 300 including a dispenser 320 for applying a layer 330 of vinyl composition as described herein, initially in a liquid form on a moving carrier web, belt, or other substrate 310. For example, the vinyl composition can be deposited on the outer face of the adhesive layer or adhesive coated release liner of the laminate. The liquid vinyl layer is passed within one or more heated region(s) or zone(s) typically provided by one or more oven(s) 340. The oven(s) heat the vinyl layer and solidify, dry, fuse, and/or cure the vinyl composition thereby forming the vinyl layer as described herein. Typically, any solvent(s) in the vinyl composition are removed. After formation of the vinyl layer, the vinyl layer, if still residing on the carrier web 310, is collected on a windup roll 350.

In certain embodiments, prior to applying a layer of vinyl composition onto a substrate, it has been found beneficial dispense the liquid vinyl composition at a viscosity within a range of from about 650 to 1,300 centipoise. However, it will be understood that the present subject matter includes deposition of the vinyl composition at other viscosities and by other deposition techniques.

In particular embodiments, it has been discovered that improved heat stability of the resulting vinyl film can be obtained by utilizing certain temperatures and/or combination of temperatures in the formation of the vinyl films. For example, subjecting the vinyl composition, in layer form on a carrier web or belt or laminate, to a first temperature of from about 250° F. to about 350° F. and particularly 285° F., for a time period of from about 10 seconds to about 2 minutes and particularly 1 minute; followed by subjecting the heated vinyl layer to a second temperature, greater than the first temperature, of from about 350° F. to about 450° F. for a time period of from about 15 seconds to about 3 minutes; has been found to produce a vinyl film with excellent heat stability and printability characteristics.

In certain versions the following heating schedules can be used: (i) heating at 285° F. for 1 minute followed by heating at 365° F. for 2 minutes; (ii) heating at 285° F. for 1 minute followed by heating at 395° F. for 30 seconds; or (iii) heating at 285° F. for 1 minute followed by heating at 410° F. for 30 seconds.

All references to heating of a vinyl layer noted herein are with regard to a layer of vinyl composition having a thickness of 1.50 mils.

As previously noted, in certain embodiments, the vinyl composition can be formed into a layer or film by applying the composition onto a substrate such as a polymeric film. In these applications, it has been found that the cast vinyl layer can retain solvent(s) that may impact UV stability and printing.

Although the vinyl films and laminates using such described herein are primarily directed for use as graphic articles applied to vehicles and signage, it will be understood that the present subject matter is not limited to such applications. Instead, the present subject matter may find wide application in a variety of other industries and uses. That is, the present subject matter also provides articles such as for example, signs, graphics, wall coverings, pressure sensitive products, banners, fleet marketing graphics, architectural coverings, consumer product labeling, and the like.

EXAMPLES

In order to further evaluate the vinyl compositions, their components, vinyl films and/or laminates of the present subject matter, several techniques were developed. Application of these techniques to the present subject matter is as follows.

Adhesion

Samples of adhesive laminates utilizing a film including (i) an intermediate molecular weight PVC resin and (ii) a bio-based plasticizer, and a layer of a permanent acrylic adhesive, were prepared as described herein. The samples were adhered to a painted aluminum substrate.

A 180 degree peel adhesion trial utilizing a peel rate of 12 inches per minute was performed in accordance with ASTM D1000.

After 15 minutes of adherence to the substrate, the samples undergoing the noted peel test, required a force of from 2.5 to 3.2 pounds-force per inch in order to peel and remove the samples from the substrate.

Removability

Samples of adhesive laminates utilizing a film including (i) an intermediate molecular weight PVC resin and (ii) a bio-based plasticizer, and a layer of a pressure sensitive adhesive, i.e., a non-permanent removable acrylic adhesive, were prepared as described herein. The samples were adhered to a painted aluminum substrate. The adhered samples and substrate were aged for 1 week at 50° C.

Upon completion of the heat aging, the samples were removed from the substrate at three angles: 90°, 135°, and 180°.

All samples removed cleanly without tearing or breaking, and without affecting the substrate in that there was no visible adhesive or plasticizer residue or staining on the substrate after removal of the samples.

3D Conformability

Samples of adhesive laminates utilizing a film including (i) an intermediate molecular weight PVC resin and (ii) a permanent acrylic adhesive were prepared as described herein. Additional samples of adhesive laminates utilizing a film including (i) an intermediate molecular weight PVC resin and (ii) a non-permanent removable acrylic adhesive were prepared as described herein. The samples were applied to painted steel corrugated substrates. The substrates included a 11/32 inch deep corrugation. The samples were adhered to a flat upper portion of the substrate and then pressed and adhered into the sides and bottom of the corrugation. FIG. 5 is a photograph of a sample utilizing removable adhesive applied to a corrugated panel. FIG. 6 is a photograph of a sample utilizing permanent adhesive applied to a corrugated panel.

The adhered films and panels were aged for 1 week at ambient temperature.

After aging, visible inspection of the adhered films revealed that the films maintained adhesion in the corrugation without any lifting or film cracking.

Tensile Strength

Samples of a film including (i) an intermediate molecular weight PVC resin and (ii) a bio-based plasticizer were prepared as described herein. Six (6) samples were subjected to tensile strength evaluation according to ASTM D1000.

The average tensile strength of the 6 samples was 3407 pounds-force per square inch with a standard deviation of 407.

Elongation

Six (6) samples of the film as described in regards to tensile strength evaluation were prepared as described herein. The samples were subjected to elongation evaluation according to ASTM D1000.

The average elongation of the 6 samples was 139% with a standard deviation of 32%.

Durability

Samples of adhesive laminates utilizing a film including (i) an intermediate molecular weight PVC resin and (ii) a bio-based plasticizer, and a layer of a pressure sensitive adhesive were prepared as described herein. The samples were adhered to a substrate. The adhered samples were exposed to high intensity UV light at an irradiance of 1,500 watts per square meter (W/m²) at a temperature of 70° C.

After 650 mega joules (MJ) of UV exposure, the delta E color change of the samples was 4.4 without any physical defects such as delamination or cracking.

Delta E is defined by the International Commission on Illumination (CIE) using method CIE76; it is the measurable difference in color of a sample.

Stress Relaxation Test

The stress relaxation test uses samples of a pressure sensitive adhesive film laminate construction with dimensions of 1×8 inch. The samples utilized a film including (i) an intermediate molecular weight PVC resin and (ii) a bio-based plasticizer, and a layer of the noted adhesive. A sample is placed in the grips of a tensile tester. The sample is stretched at a rate of 4 inches per minute to an elongation of 13% and held for 12 minutes. The tensile force is recorded at the beginning and end of the 12 minute hold. The stress relaxation result for the bio-based pressure sensitive adhesive film laminate is 72%. The initial force at hold was 1.46 pound-force. The final force was 0.41 pound-force indicating a retained force of 28% or stress relaxation of 72%. This is the average of 3 tests with a standard deviation of less than 0.1.

Color Test

Color is measured by the CIELAB color space with a spectrophotometer according to industry standard ISO 13655. A bio-based film as described herein and utilized in this evaluation was transparent, so the color was measured on a uniform white background. The color measurement of the bio-based film on the white background has a L* value of 88.56, a* value of −1.33, and b* value of 1.38. The most significant part of this color measurement is the b* value which is an indication of the amount of yellowness, which a bio-based plasticizer can directly affect. The white background alone has a b* value of 0.91 so the bio-based film contributed 0.47 units of b* yellowness which is not a significant value. This indicates that the bio-based plasticizer is not having a negative effect on the color of the film.

Many other benefits will no doubt become apparent from future application and development of this technology.

All patents, applications, standards, and articles noted herein are hereby incorporated by reference in their entirety.

The present subject matter includes all operable combinations of features and aspects described herein. Thus, for example if one feature is described in association with an embodiment and another feature is described in association with another embodiment, it will be understood that the present subject matter includes embodiments having a combination of these features.

As described hereinabove, the present subject matter solves many problems associated with previous strategies, systems and/or devices. However, it will be appreciated that various changes in the details, materials and arrangements of components, which have been herein described and illustrated in order to explain the nature of the present subject matter, may be made by those skilled in the art without departing from the principle and scope of the claimed subject matter, as expressed in the appended claims. 

What is claimed is:
 1. A composition comprising: from about 70% to about 90% of one or more intermediate molecular weight PVC resins having a molecular weight in a range of from about 102,000 to about 134,800; from about 10% to about 30% of one or more bio-based plasticizers; at least one UV absorber; at least one hindered amine light stabilizer; at least one heat stabilizer; at least one acid scavenger.
 2. The composition of claim 1 wherein the amount of the one or more bio-based plasticizers is within a range of from about 20% to about 25%.
 3. A film comprising: one or more intermediate molecular weight PVC resins having a molecular weight in a range of from about 102,000 to about 134,800; a bio-based plasticizer, the plasticizer at a concentration within a range of from about 25 phr to about 35 phr based upon the PVC resin.
 4. The film of claim 3 wherein the film further comprises: at least one agent selected from the group consisting of (i) a UV absorber, (ii) a hindered amine light stabilizer, (iii) a heat stabilizer, (iv) an acid scavenger, and (v) combinations of (i)-(iv).
 5. The film of claim 4 wherein the film comprises a combination of (i), (ii), (iii), and (iv).
 6. The film of claim 3 wherein the film is produced by a casting process.
 7. A laminate comprising: a vinyl film including one or more intermediate molecular weight PVC resins, and at least one bio-based plasticizer; a layer of a pressure sensitive adhesive; wherein the molecular weight of the intermediate molecular weight PVC resin is from about 102,000-134,800, and the concentration of the bio-based plasticizer in the vinyl film is within a range of from about 25 phr to about 35 phr based upon the intermediate molecular weight PVC resin.
 8. The laminate of claim 7 wherein the vinyl film further includes at least one agent selected from the group consisting of (i) a UV absorber, (ii) a hindered amine light stabilizer, (iii) a heat stabilizer, (iv) an acid scavenger, and (v) combinations of (i)-(iv).
 9. The laminate of claim 8 wherein the vinyl film includes a combination of (i), (ii), (iii), and (iv).
 10. The laminate of claim 7 wherein the vinyl film is produced by a casting process.
 11. The laminate of claim 7 wherein the laminate exhibits a tensile strength within a range of from about 3,000 pounds-force per square inch to about 3,900 pounds-force per square inch.
 12. The laminate of claim 7 wherein the laminate exhibits an elongation of about 105% to about 175%.
 13. The laminate of claim 11 wherein the laminate also exhibits an elongation of about 105% to about 175%.
 14. The laminate of claim 7 wherein after adhesion to a substrate and 650 mega joules of exposure to UV radiation at an irradiance of 1,500 W/m² at a temperature of 70° C., the laminate exhibited a delta E color change of from 4.0 to 4.8 without any physical defects including delamination from the substrate and cracking of the laminate.
 15. The laminate of claim 14 wherein the laminate exhibits a tensile strength within a range of from about 3,000 pounds-force per square inch to about 3,900 pounds-force per square inch.
 16. The laminate of claim 14 wherein the laminate exhibits an elongation of about 105% to about 175%.
 17. A method for producing a vinyl film, the method comprising: forming a layer of a vinyl composition in liquid form on a substrate, the vinyl composition including at least one intermediate molecular weight polyvinyl chloride (PVC) resin, at least one bio-based plasticizer, at least one UV absorber, at least one hindered amine light stabilizer, at least one heat stabilizer, at least one acid scavenger; heating the layer of the vinyl composition to a first temperature within a range of from 250° F. to 350° F. for a time period of from 10 seconds to 2 minutes to thereby form an intermediate vinyl layer; heating the intermediate vinyl layer to a second temperature within a range of from 350° F. to 450° F. for a time period of from 15 seconds to 3 minutes to thereby form the vinyl film. 